Port-xen archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: xennet performance collapses with multiple vCPU



On Wed, 25 Mar 2020, Jaromír DoleÄ~Mek wrote:
Le mar. 24 mars 2020 à 15:13, Stephen Borrill <netbsd%precedence.co.uk@localhost> a
écrit :

All using NetBSD 9.99.51 (XEN3_DOMU) #0: Sun Mar 22 17:35:29 UTC 2020

Note that increasing the vCPUs from 1 to 4 (2 gives same result as 4)
drops the throughput to about 10%. No offloads configured in domU:


I found out the problem appeared between 2020-01-08 00:00 (that was still
good) and 2020-01-14 00:00 (that is already bad).

There were some CPU scheduling changes by Andrew Doran around that time, so
it's likely the culprit.

I'm working on bisecting this further. It's complicated, between 01-08 and
01-14 there were some bugs which prevent the Xen DomU MP kernel from
booting.

Well, that's reassuring for me as none of my machines run -current. I thought that running a -current kernel for the benchmarking I wanted to do would be a good idea because of your recent changes. I should have also checked with the original netbsd-9 kernel on the machine.

--
Stephen


Home | Main Index | Thread Index | Old Index